[algino289]

Dear All,

I am driving a 2020 X5 40I Xdrive and recently just replaced the ZF LG 8 transmission oil at 100k mileage.

However, right after the transmission oil replacement, I immediately felt that my car is a bit sluggish and the throttle response are not as quick as before the transmission oil replacement.

My gearbox is GA8HP51X and the transmission fluid part number is 83222289720. I have checked online and found both ZF 8 and ZF LG9 also carry this OEM number : (

And now I am a bit confused here and not sure did I went with the wrong transmission oil that caused the sluggishness of my gearbox ??

I would be very much appreciated it if someone can enlighten me a bit more on this as I really cant find useful information online to clear my doubt here.

Thanks in advance !

[Bking60]

Did you replace the whole lower housing with the integral filter?
Did you run the car through the gears for about 5 minutes and leave running as you topped off the fluid?
ZF9 is same except more viscous at 40C but same at 100C as per an F30 post I read. Additives are the same.

[algino289]

Yes I did replace the oil pan filter and topped up the fluid as it should after gear warm-up for abt 5-10 minutes.

I suppose my car should feel lighter and more responsive after the new transmission oil replacement but too bad it happens reversely instead : (

I can only assume that maybe ZF LG 9 should be the more appropriate transmission oil to be replaced than LG 8 for my gearbox ?? so far my gearbox performance still smooth as silk but just not as responsive as before.

Originally Posted by Bking60

Did you replace the whole lower housing with the integral filter?
Did you run the car through the gears for about 5 minutes and leave running as you topped off the fluid?
ZF9 is same except more viscous at 40C but same at 100C as per an F30 post I read. Additives are the same.

[swainbmw]

I’ve been down this road before when you do a transmission service on high mileage cars nine out of 10 times that transmission will fail . What should been done is use half of the old oil with the new oil . A blend to keep this transmission happy and hopefully they did not use a pump to clean out the system, because those are detrimental to transmissions with high mileage. A 100,000 is considered high mileage, and most service centers would suggest not to touch it. What I typically do is service them around 45,000 miles or I don’t touch.

[weinerbarn]

Per TIS ...

"To set the correct oil level, it is mandatory that the service function "Transmission control unit: Oil-level adjustment" is carried out with the diagnosis system."

There's a procedure that is supposed to be run in ISTA after servicing.

[algino289]

Think you are right mate.. My workshop only replaced the transmission oil and filter pan manually without using any ISTA software to run through the oil level adjustment process.

Guess I can only wait for my gearbox to adapt to new transmission fluid over the time

Originally Posted by weinerbarn

Per TIS ...

"To set the correct oil level, it is mandatory that the service function "Transmission control unit: Oil-level adjustment" is carried out with the diagnosis system."

There's a procedure that is supposed to be run in ISTA after servicing.

[Stinkyxy]

Whatever you do don’t reset transmission adaptation. That’s only for rebuilds.

I would warm up car and try to rp it off. Use ista to make sure temp is in rqnge and then add more fluid. Likely the converter took some fluid.

Since you didn’t flush it you’ll be fine.